Hot Houston Attic
I have a 2400 sq ft, 1 story home in Houston, TX.
The A/C runs for 15-17 hours per day.
My attic gets to 135 degrees F on sunny days when we get to 100 degrees.
I have 5 passive vents in the roof.
Would installing electric fans (probably 2) in the roof vents help me reduce my cooling bills?
Would the decrease in A/C usage be offset by the electricity used by the fans?
Thanks in advance,
no...........u need to find a reputable contractor.....unit stays on for 15-17 hours........wont satisfy tstat...could be anything..charging issue dirty coil...bad airflow..............good luck
2 fans can use almost as much energy as A/C
There was a study done in Austin that proved that power vents cost you more than they save. In fact they actually pulled your cold air from the house to the attic.
You need to make sure you have sufficent soffit venting and that it is clear. Consider having a radiant barrier applied, either a spray on or when you have the roof replaced.
How much attic insulation do you have, you should have R-19 to R-22 if you have a radiant barrier or R-33 if no RD.
It would not be unreasonable for a system to be running the hours yours is right now with the level of heat we are having in Houston. What temperature are you trying to maintain. If it is in the mid to low 70's you are asking to much of the system when it is 98* +.
You may also have a performance issue due to an ill performing system, an evaluation may be a good idea. What part of town are you in we can recommend a local contractor, there are more than a dozen Houston contractors on this site.
Add more insulation to your attic and think about having a continuous ridge vent put on your roof as long as you have the proper soffit vent already will reduce the heat load in your attic. Do you have the shades pulled during the daytime ? Shade trees in your yard on the East & West side of the home ? Small appliance's tunred off unless your using them, Door's & Windows properly sealed thur out your home will reduce the heat load. Any insulation in your walls ?
I live 35 miles west of Houston and would never recommend a powered attic vent (PAV). There may be a few rare cases where they can save money but the great majority of times they will increase infiltration from outside, into your house. With our humid outside air, you don't want that.
Published studies all tend to the same answer, that PAVs consume more energy than they save. Consider installing radiant barrier instead, studies tend to show 10% or so cooling energy savings. I wonder how many KWH per month your bills run?
Even higher priority, if you (with an AC pro) can find and fix any duct leaks in the attic. Next but still high priority, any improvements you can make to airtightness in your house. I am a homeowner who has worried about these kinds of efficiencies. Only after that, do I believe insulation will be worth buying. People sometimes talk about insulation as if it is the cure-all but when I installed insulation without the other things in a house long ago, could see no improvement in my bills.
Hope this helps -- Pstu
This is my first full summer season W/O my PAV's....I can tell a difference, especially with the indoor RH....Trust the people on this forum when they are telling you not to use a PAV...I'm here to say they are right...
God bless Joe. Regards TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
Attic Gable fans also?
Would an attic gable fan meet your definition of a PAV and if so, your advice is to terminate use?
Originally Posted by Joe Mascitti
i don't think 15-17 hours a day is out of order in houston. 135 degrees isn't either,but the attic temp you can do something about. houston heat & humidity not so much. radiant barriers do work, take it from people who work in attics. more insulation can't hurt either. good luck.
"When the people find they can vote themselves money,that will herald the end of the republic" - Benjamin Franklin
"Government is not reason, it is not eloquence, it is force;like fire, a troublesome servant and a fearful master. Never for a moment should it be left to irresponsible action"- George Washington
if you install a radiant barrier it will reduce attic temps by 30 degrees.
beware of rb companies that say it will reduce energy consumption by 30%
it is not the same thing.
there is a thread here where a home study is being done by one of the pro members
monitering temps in attic, I think his is a spray on rb, so I am very interested
in his findings, as I am a firm believer in a single sided foil rb that is attached to the
underside of the roof rafters.
take a look at it when you have time.
the difference my single sided foil rb made in my house is amazing!
and yes...pav's are a waste of money and make more problems than they solve.
ductleakage & house leakage are worse when attic is under a negative pressure.
(which is what pav's do..)
best of luck to you.
The cure of the part should not be attempted without the cure of the whole. ~Plato